1. Field of Invention
The present invention relates to an optical projection apparatus, and particularly to an optical projection apparatus with smaller size and thickness.
2. Description of the Related Art
FIG. 1A and 1B are schematic structure drawings of two conventional optical projection apparatuses. Referring to FIG. 1A, a conventional optical projection apparatus 100a includes an illumination system 110a, a digital micro-mirror device (DMD) 120 and an imaging system 130. The DMD 120 is disposed between the illumination system 110 and the imaging system 130. Wherein, the illumination system 110a includes a light source 112, a light integration rod 113, a plurality of lenses 114 and two reflective mirrors 116a and 116b. The light source 112 is suitable for providing a light beam 11 2a, which passes through the light integration rod 113 and the lenses 114, then is reflected by the reflective mirror 116a onto the reflective mirror 116b and reflected by the reflective mirror 116b onto a lens 114 adjacent to the DMD 120. Further, the light beam 112a is incident into the DMD 120. The DMD 120 converts the light beam 112a into an image 112a′ therein and makes it incident into the imaging system 130. Then the image system 130 projects the image 112a′ on a screen (not shown).
Referring to FIG. 1B, it is similar to FIG. 1A except the illumination system 110b in the optical projection apparatus 100b includes a light source 112, a light integration rod 113, a plurality of lenses 114 and a reflective mirror 116a. The light beam 112a provided by the light source 112 passes through a light integration rod 113 and lenses 114, and then is reflected by a reflective mirror 116a into a digital micro-mirror device (DMD) 120. The DMD 120 converts the light beam 112a into an image 112a′ therein and makes it incident into the imaging system 130. Then the image system 130 projects the image 112a′ on a screen (not shown).
In the above-described two optical projection apparatuses 100a and 100b, the optical axis of the imaging system 130 and the optical axis of the digital DMD 120 are parallel to each other, so that a big, unused space 50 is created between the imaging system 130 and the illumination system 110a/110b. That is why the conventional optical projection apparatuses 100a and 100b are bulky with a big size and thickness. Obviously, such conventional design does not meet the compact size requirement in the modern electronic products.